Democratic Party fund-raiser Nathan Landow hired a private investigator for a project involving Kathleen E. Willey, the former White House volunteer who has testified that President Clinton groped her, the private eye said yesterday.

Independent counsel Kenneth W. Starr has been investigating Willey's claims that Landow and others tried to influence or intimidate her to chill her testimony about Clinton when she was a witness in the Paula Jones case.

Jarrett Stern, a private investigator, told ABC News in an interview broadcast last night that he was hired for an unspecified project by Landow, a wealthy Maryland developer who has raised hundreds of thousands of dollars for Clinton-Gore campaigns. Stern's lawyer, Edouard Bouquet of Bethesda, told the network his client felt uneasy about what he was asked to do and called Willey, using an alias, to warn her someone was out to do her harm.

"I think that he perceived a situation where he was being asked to do something he wasn't comfortable with," Bouquet said of Stern. The lawyer declined to be more specific.

Landow flatly denied he engaged any private investigator to look into Willey's life or background. "Absolutely not," Landow said. "There is no evidence, no allegation, no proof on me." Landow's lawyer, Joe Caldwell, said he could not comment on Stern's claims because of Starr's ongoing criminal investigation, but Caldwell added, "There is absolutely no issue here."

Landow refused to testify before Starr's grand jury last summer, citing his Fifth Amendment right against self-incrimination. He has denied any wrongdoing and said he invoked the right on the advice of lawyers when prosecutors refused to give him immunity in exchange for his testimony about his dealings with Willey. He has described her as a social friend he met through his daughter, who also worked as a White House volunteer.

Stern declined to detail what he had been asked to do in connection with Willey, but he told ABC that he "wholeheartedly" believes that Willey was approached with a menacing message by a stranger jogging near her Richmond home two days before her Jones case testimony. Willey has said the man inquired about her children by name, about her missing cat and about whether she'd gotten the tires on her car repaired after they were mysteriously vandalized by someone who drove masses of nails into all four of them. "Don't you get the message?" she has said the man asked.